\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{circuitikz}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes}
\ctikzset{bipoles/length=1cm}
\begin{document}
\small
\begin{circuitikz}[>=latex, scale=1.0,european]
  % \useasboundingbox(0.9,0)rectangle(5.1,5);
  \draw(0,0)to [R=$R_2$] (6,0);  \draw [->](0,0)--(.5,0)node [above]{$I$};
  \draw [->](1,0)--(1.75,0)node [above]{$I_2$};
  \draw [->](1,-1.0)--(1.75,-1.0)node [above]{$I_3$};
  \draw [->](1,1.0)--(1.75,1.0)node [above]{$I_1$};
  \draw (1,0)--(1,-1.0) to [R=$R_3$] (5,-1.0)--(5,0);
  \draw (1,0)--(1,1.0) to [R=$R_1$] (5,1.0)--(5,0);
  \draw [->](5,0)--(5.5,0)node [above]{$I$};
  \draw [fill=black](1,0) circle (2pt); \node at (1,-.25)[left]{$A$};
  \draw [fill=black](5,0) circle (2pt); \node at (5,-.25)[right]{$B$};
  \draw (1,-1.2)--(1,-1.9);\draw (5,-1.2)--(5,-1.9);
  \draw[<->](1,-1.7) to node [above]{$U$} (5,-1.7);
\end{circuitikz}
\end{document}